Hello,


My (beloved and long missed) ’95 3UX XT600 is suffering some overheating and a geabox issues. I have been looking around, but could not find an answer, so I’d be really grateful for your advice/knowledge.

a) Riding alone, not loaded and not revving at all, at an average 60-70km/h in low traffic, just a few red lights and open road, and in Swiss summer (not hot), it is a matter of time (10-15kms?) to reach ca. 110ºC (I stopped right before). Should as cars run at 90ºC, 110ºC is very hot and 120ºC is STOP right now?

b) In addition, when I engage 5th gear it starts to sound as “brushing/rubbing” (rozar in Spanish, frotter in French, I do not know in English, sorry). It only happens when accelerating, no matter the speed. If I go downhill and release the gas, no sound, just touch the gas, it starts. So, I’ve just riding on 4th gear. And, ironically (I think, as oil will be more liquid?), when I ride for a while and it warms up, gears are much harder to engage.

Last year I changed oil and filters and added an oil thermometer and an oil plug with a magnet to control temperature and to prevent possible iron fillings to move around in the oil. I just rode it short distances and very gently, but did not try to get it fix just to park it right after for 1 year.

Again, I can feel how it gets hotter in my tights and just have to look at the thermometer to confirm it. The bike doesn’t “want” to be accelerated anyway, just low rev and does not run well as it used to (when it was a pleasure to feel the single tok, tok, tok…). Now it vibrates awkwardly.

I just guess something like “valves adjustment” needed and 5th gear to be replaced, but I lack the knowledge to diagnose at all.:confused1:

Any idea of what all this may be? Thanks a lot in advance.


Esteban

PS: I was just dreaming of getting it back running, so I am just really f**ked now, sorry for the expression, since I just lack the money to fix anything expensive now...

Hi, I live in Denmark, so we should have about the same temperatures. Yours sound a bit warm, but nothing too serious. I've hit 120c on the interstate running only 100km/h in the summer. Nothing bad will happen. A fellow of mine once had a small-ish car with a oilthermometer (came like that from the factory). It "redlined" at 140c...

I know next to nothing about youre 5th gear, but it certantly sounds like you need to replace it. So on to the heat....

How long since you replaced motoroil, and which do you run? Have you checked that you have the right amount of oil? Running low should make the temperatures climb. I use 10w50 fullsynthetic from www.louis.de i use theire housebrand "Procycle" and change it at 3500-4000km, but looking at the oil I would guess I could go way beyond that, but oil is cheap, a motor is not. Better safe than sorry as they say.

How about valves, how long since last checked? I would check them just to rule them out.

Do you have stock gearing? Smaller front sprocket or bigger rear will make the bike rev more, creating more heat. Even a big rear tire can alter the gearing some. My big ass 17" knobby is actually as big as a 18" stret-tire.

Lastly, how about jetting, is the bike stock and/or have someone fiddled with the carb? Th xt's tend to run rich to cool the bike, but they're not that rich in the idle curcuit, so perhaps an adjustement of youre mixturescrew could help a tad.

You could also have an airleak around the carbs, leaning out the mixture a lot, creating more combustionheat.

It may sound like much, but most of it is quick to test and/or fix.

Good luck.

Hi Jens,

Thanks for your quick reply. I thought that since engine and gearbox share the same oil, a problem in the gearbox could lead to higher oil temperature, but the 5th gear should not be turning at all, so shouldn’t be the cause.

I have had some old cars running very hot (R4 and R5), so I got used to drive them gently to keep them cool, so I do the same with the bike (already last year). Otherwise, I would go much hotter. Anyway, thanks for telling me “take it easy, Esteban, no worries”.

As for the sprockets, I just have no idea. I should count them (it is parked in the office now). I got it 2nd hand with lots of modifications; the previous owner rode it to India 14 years ago. But it run just great when I got it (Touring Club tested it and told me: it is in excellent condition! Swiss German guy took good care of it). Just my last year’s fault: I almost run out of oil in the Pyrenees (I had just ruined a chain in Perpignan, stupid me!).

Carb jets, no idea either.

Oil: just changed by Yamaha dealer (damn expensive) this week. I brought it to prepare it for MOT, but I cannot pay those HUGE bills. First and last time. I will have to wait for the other mechanic to come back from holidays… I hope I won’t get mad in the meantime! I actually want to work on it, but I do not have a place (I’d really love to make it into small pieces and look inside and assemble it!)

First off.... Semi-synthetic ONLY or you will have the clutch slipping, gears slipping-jumping around!


And that oil temperature seems just about right!

Your no-acceleration problem could simply be either your carb jetting or it just being dirty!

Also, remove and check the color of your sparkplug.
Replace it with a new one!


Vando

New sparkplug, just changed by Yamaha dealer... I took it for a full service for MOT (but had to stop it $$$$$!!! just oil, oil filter and sparkplug).

I will get it, ride normally (no preventive) and see how high it gets (when is it time to stop?). It is not I saw temperature rising and I worried, but the other way around: something going wrong, feeling it hotter and then buying the thermometer.

Muito brigado pelo conselho, Vando...

I call huge BS, sorry to say so...But I do. If you have personal experience, please tell us, would love to hear it.


Fullsynthetic is not more "slippery" its just not degrading as fast as semi. It "keeps" its specs for longer time than semi.

I use only fullsynthetic, have tried 4-5 brands over time, and many more different types of oil (viscocity) none have given me trouble.

I have 93k on mine now, on stock everything motorwise, should count for atleast a little.

Not trying to be an ass, just trying to proove my point.

I used to have 10w30 or 10w40 fully synthetic and I had exactly what I mentioned above.
After changing to semi-synthetic not one single problem after that.

So yes, that's my POV...oh, and I believe the same as the workshop manual? :P

Mine started to run poorer when I changed the oil for a Polo Motorrad. I will check if it was olive oil or rapeseed oil... ;-)